Furnace



C. STEIN FURNACE Dec. 8, 1931. 1,835,677

Filed March 8, 1928 Figi v sku-g :INVE TQR I V- LMU' MJ Gm' l 5 1 of suitab Patented Dec. 8, 1931 UNITED STATES .PATENT 1 OFFICE.

STEIN, or raars, mNcE, AssIoNoB. r.ro 'SOCIETE ANoNYME Das mums DE MANUTENTION Er Fours STEIN, or rams, FRANGE, A CORPORATION or FRANCE.

FUBN'ACE Application led March 8, 1928, Serial No. `260,110, and in France March 21, 1927.

f This invention relates particularly to a furnace operated by means of lean combustible gases such as blast furnace gas and aims to enable a relatively high temperature to be 5 maintained in the heating chamber, notwithstanding the fact that the gas may be so poor as lnot to be capable of producing such temperatures under ordinary conditions or operation.

In accordance with the present invention, a portion of the lean gas supplied is diverted from passage to the main heating chamber, and burned separately to act as a source of heat for an air preheater, thereby producing 115 air preheated to such temperature that, when mixed in the main heating chamber with'the lean gas which is fedinto such chamber, the temperature of the gases of combustion is sufficient to maintain a relatively high tem- 20 perature in the main heating chamber. For

example, with the use of blast furnace gas l under ordinary conditions of operation, it is impossible to obtain a heat high enough for billet heating or similar rolling mill opera- 26 tions and the present invention will enable heating temperatures ranging up to 2500 F. or more to be obtained, thus malng lean 'gases available for furnaces 'where temperatures of the above range are desired.

$ Further objects and advantages of the invention will be in part obvious and in part specifically pointed 'out in the description hereinafter contained which, taken in conjunctionv with the accompanying drawings,

SI5v discloses a furnace adapted to be o erated in accordance therewith. It should e underf stood, however, that such disclosure is merel0 Fig. 1 is a central vertical sectional view of a furnace constructed to operate in accordance with the invention.

Fig. 2 is a transverse vertical section on line 2-2 of Fig. j Fig. 3 is a section similar to on line 3-3 of Fig. 1. Fig. 4 is a horizontal section taken 4.-'-4 of Fig. 1.

Referring to the drawin e construction 1s shown as dis- Fig. 2 but taken on line a recuperatoi` rises vertically through the recuperator as it takes up heat and is collected in a gathering chamber 3 at the top of the recuperator. The illustrated form of the invention, as will be'apparent from Fig. 3, shows twin recuperators disposed side by side.

F rom the gathering chamber or chambers 3, the preheated air Ypasses upwardly froma transverse condit 4 to a similar conduit 6, the distribution of the flow of preheated air between the two conduits being controlled by.

dampers 5 (Fig. l) disposed across the furnace. The preheated air then passes through l a passageway 7, disposed adjacent an auxiliary combustion chamber 18 hereinafter described, and ports 7a permit the preheated air to pass from this into the main combus# tion chamber 22, or into a mixing chamber 8 associated therewith.

If desired, a portion of the preheated air from passageway 7 may be directed through ports 9 to mix with the lean gas which is diverted from its source of supply 11 (Figsf 1 and 2) through branch pipes 16 controlled by .dampers 17, to pass through ports and mix with the preheated air entering through ports 9 and burnin the auxiliary chamber 18. The hot gases then pass through a conduit 19 into the top of the recuperator and travel horizontally across and down through the recuperator in zig-zag fashion, being finally drawn out through an exhaust flue 20 at the bottom, the distribution of flow of the heat- Y mg gases being ,preferably regulated by dampers 21 (Fig. 1) disposed across the recuperator. t

The lean gas commg from source of sup.

ply 11, which is used for main heating pur;

poses,'passes in through pipes 11, having dampers 12 for distribution purposes (Fig, 2)

'A to transverse chambers 13A and 14 havmg f dampers 14jl interposed therebetween, to distribute the flow and from thence into the chamber 8 -where the lean gas mixes with the preheated air coming from recuperator 1 above described, and the gases of combustion travel through `the main heating chamber 22, which in the present instance is illustrated as for billet heating purposes, until/the spent gases finally pass out through an exhaust 10 ue v'15 located at `the delivery end of the heatin chamber. As a ove stated the diversion of `a portion ofthe lean gas supply to burn thelatter for preheating purposes in auxiliary combus;

tion chamber 18, permits the temperature maintained in the main heatin chamber, by combustion ofthe remainder o the lean as with the air so reheated, to be much hig ler than could be' o tained by burning the lean.

gas in the-ordinary manner. The various dampers above described also permit the ow of the as and preheated air to be proportioned tweenthe different purposes for which it is tobe used in such manner that 2'5 uniformly controlled conditions of operation may be maintained. It will also be noted that-the described relative disposition of the recuperator, auxiliary chamber and main combustion chamber causes the preheated air to flow past and over the auxiliary combus.

' tion chamber, wherebyit may ta heat radiated from the latter.

While a preferred embodiment of the in- 1vention has been described it will be obvious that many changes may be made therein without departing from its principles as set forth in the appended claims.A f

I claim: p f 1. A furnace of the class described heated 40 bylean gas of the blast furnace gas type,

having a main combustion chamber, a conduit adapted to connect the same with a source of such gas supply, an auxiliary combustion chamber also connected with said source, an air preheater laterally spaced from .said auxiliary chamber and adapted to be heated b the gases of combustion passing from sai auxiliary combustion chamber, preheated air passageways of said preheater leading to the main' combustion chamber to e up the mix such preheated air with the gaseous fuel entering said main combustion chamber from said source ofsupply.

2. A furnace of the class described heated by lean gas'of the blast furnace gas type,

having a 'main combustionvchamber, a conduit adapted to connect the same with a source of such gas suppl an auxiliar combustion chamber locatedybeneath sai main combustion chamber and also communicating with said source of combustible gas, a recuperator also located beneath said mainv combustion chamber and laterally spaced v from said auxiliary combustion chamber toing passageways of said recuperator with said auxiliary combustion chamber and the heated gas passageways of said recuperator A to the, main combustion chamber to mix the preheated gases with the gas entering such main combustion chamber. y

3. A furnace of the class described heated by lean gas-of the blast furnace gas type, having a main combustion chamber, a conduit adapted to connect the same with a source of such gas supply, an auxiliar combustion chamber also connected wit said source, an air preheater laterally spaced from said auxiliary combustion chamber and adapted to be heated by-the gases of combustion passing from said auxiliary combustion chamber, preheated air passageways of said preheater leading past said auxiliary combustion chamber so as to take up heat radiated therefrom, and from thence to the main combustion chamber to mix such preheated air with the gaseous fuel enteringsaid main combustion chamber from said source of supply. f

4. A furnace of theclass described heated by lean gas of the blast furnace gas type having a main combustion chamber, a conduit adapted to connect the same with a source of such gas supply, an auxiliary combustion chamber located beneath said main combustion chamber and also connected with said source, a recuperator also located beneathsaid main combustion chamber at one side of said auxiliary combustion chamber and connected with said auxiliary combustion chamber to receive the heated gases passing therefrom at the top of the recuperator and discharge said gases from the bottom of the recuperator, said recuperator being constructed to receive the air to be preheated adjacent its bottom and discharge the same from its top 'into the main combustion chamber adjacent the point of entry ofthe combustible gas.

. 5. A furnace of the class described having a main combustion chamber, a conduit adapted to connect the same with a source of combustible gas, an auxiliary combustion chamber also connected with said source, an air preheater adapted to be heated by the gases of combustion passing from said auxiliary combustion chamber, preheated air assageways of said preheater leading to t e main combustion chamber to mix such preheated air with the gaseous fuel entering said main combustion chamber from said source of supply, and one or more preheated air passageways of said preheater leading to said auxiliary combustion chamber.

-In testimony that I claim the foregoing, I have hereunto set my hand this 20th day of February, 1928. l

' CHARLES STEIN.

69 gether with meansfor .connecting the heat- 

